Communication method and communication apparatus

ABSTRACT

The present disclosure provides an orthogonal codes based code division multiplexing method of performing the code division multiplexing of demodulation reference signals in multiple layers of resource blocks by using orthogonal matrices, the method comprising: changing the order of chips in particular rows of a first orthogonal matrix to obtain a second orthogonal matrix with the changed order of chips; and multiplying the chips in respective rows of the second orthogonal matrix by the demodulation reference signals in corresponding layers of resource blocks correspondingly in the time direction to obtain code division multiplexing signals. The technical scheme of the present disclosure can improve the power jitter situation of downlink signals on the time, thereby the usage efficiency of the power amplifier at the base station side can be improved.

TECHNICAL FIELD

The present disclosure relates to signal multiplexing techniques andde-multiplexing techniques of the communication field.

BACKGROUND ART

Orthogonal codes based Code Division Multiplexing (CDM) techniques arewidely applied in the technical field of wireless communication. Themost classic CDM technique is to expand different signals by usingdifferent orthogonal sequences, and superpose them so as to eliminateinterferences between the superposed signals by means of the orthogonalproperty among different sequences. Because of this advantage, the CDMtechniques are widely applied for multiplexing different signals in thewireless communication system.

FIG. 1(A) to FIG. 1(D) are diagrams showing the principle of the CDMmultiplexing using four-dimensional Walsh codes. As shown in FIG. 1(A),the code words used in CDM are orthogonal to each other, which meanscorrelations between the different code words are zero. As shown in FIG.1(B), in the CDM multiplexing, different signals S1, S2, S3, S4correspond to different code words respectively, and the differentsignals are respectively multiplied by chips in the corresponding codewords. The result of the multiplication produces expansions of signals.The expansions produced by the different signals are superposed to formthe multiplexed signals W, X, Y, Z. As shown in FIG. 1(C), themultiplexed signals W, X, Y, Z are transmitted on a communicationchannel. The expansions of signals by CDM may be performed either on thetime domain or on the frequency domain. As shown in FIG. 1(D), in theCDM de-multiplexing, the signals after the CDM expansion are correlatedwith the corresponding code words to recover the original signals S1,S2, S3, S4.

In the CDM multiplexing using orthogonal codes, the orthogonality amongthe different orthogonal code words is the most essential characteristicof the conventional orthogonal CDM. In the wireless communication, themost widely used orthogonal code is Walsh code, and the length of suchcode can be 2, 4, 8, 16 . . . (a power of 2). The different orthogonalcode words may form an orthogonal matrix.

FIG. 2 is a schematic diagram showing that different base stationstransmit multiple data streams to a mobile terminal in a wirelesscommunication system.

As shown in FIG. 2, adjacent base stations 201 and 202 may includemultiple antennas respectively, and transmit multiple data streams to amobile terminal 203 in a way of spatial multiplexing respectively. Thedata streams may be divided into multiple layers, for example, each datastream may include two or more layers of data stream. Here, it is shownthat each data stream includes a first layer of data stream and a secondlayer of data stream respectively.

FIG. 3 is a diagram showing an example of a resource block constitutinga data stream transmitted to a mobile terminal from a base station in awireless communication system.

In FIG. 3, one resource block (RB) constituting a data stream is shown.The horizontal axis of the resource block represents time, while thevertical axis represents frequency bandwidth. The horizontal axis isdivided into 14 segments, each of which forms one OFDM symbol along thevertical axis beginning at the horizontal axis. The vertical axis isdivided into 12 segments, each of which is one sub-carrier along thehorizontal axis beginning at the vertical axis. Each of small squares inthe resource block represents one resource unit. All of 12×14 resourceunits in the resource block constitute one sub-frame on the horizontalaxis. The first three columns of the resource units in the resourceblock constitute a control region for transmitting control data. Otherresource units without grid lines are used to transfer data signals. Inthe same base station including multiple antennas, for example, in thebase station 201, the multiple data streams may be transmitted to themobile terminal 203 in a way of spatial multiplexing. The multiple datastreams are located at different layers respectively, and each layer ofdata streams of the resource block may use the same time and frequencyresources. For example, the multiple antennas of the base station 201may transmit two layers of data streams, that is, a first layer of datastreams and a second layer of data streams, to the mobile terminal 203through spatial modulation, and the corresponding resource blocks ineach layer of data streams may be located at the same time and frequencyresources, that is, at the same time and frequency but using differentpre-coding manners.

Resource units 301 represented by grid lines are used to transmitdemodulation reference signals (DMRS) of a dedicated channel specific toa cell, the demodulation reference signals are used to demodulate datasignals transferred in the resource block in a mobile terminal. Here,each resource block includes multiple demodulation reference signalswhich are distributed at predetermined time and frequency positions. Inorder to correctly demodulate the data in the multiple layers superposedon the time and the frequency, the LTE-Advanced provides thedemodulation reference signals (DMRS) which are orthogonal with eachother for the superposed data layers.

FIG. 4 shows an example that the different layers of demodulationreference signals are multiplexed by using an orthogonal matrix.

FIG. 4 is an instance in the LTE-A Release-9 standard. In FIG. 4, Walshcodes with the code length of 2 such as [1, 1] and [1, −1] are used tomultiplex two layers of demodulation reference signals orthogonal witheach other. Specifically, the Walsh code [1, 1] is multiplied byrespective demodulation reference signals in the first layer of theresource block, and the second code [1, −1] of the Walsh matrix ismultiplied by respective demodulation reference signals in the secondlayer of the resource block.

FIG. 5 shows a sectional diagram of a resource block after Walsh codeswith the code length of 2 such as [1, 1] and [1, −1] are used tomultiplex two layers of demodulation reference signals.

The result after multiplexing two layers of orthogonal demodulationreference signals on one resource block is as shown in FIG. 5. For thesake of clarity, FIG. 5 shows only a part of the resource block. In FIG.5, it is assumed that the pre-coding factor for demodulation referencesignals in the first layer of the resource block is A, and thepre-coding factor for demodulation reference signals in the second layerof the resource block is B. In the adjacent two OFDM symbols placed withthe demodulation reference signals, one always has a value of A+B, theother always has a value of A−B. When A=B, one symbol always has a peakvalue of (A+B), and the other symbol has always a value of zero.However, in order to ensure the usage efficiency of a Power Amplifier(PA) in a base station, power fluctuation on the time (that is, betweenthe different OFDM symbols) of emission power is required to be aslittle as possible. If the above mapping manner from the orthogonalmultiplexing codes of the demodulation reference signals to the resourceblock is employed, when A=B (as shown in FIG. 5), peak values and zerovalues alternately appear in the OFDM symbols containing thedemodulation reference signals, which will cause the power fluctuationbetween the different OFDM symbols increasing. In order to address theproblem, a mapping manner as shown in FIG. 6 is actually employed in theLTE-Advanced Release-9.

FIG. 6 shows an actual mapping manner of the code division multiplexingbased on the orthogonal codes in the LTE-A Release-9.

In FIG. 6, RB1 and RB2 are two resource blocks adjacent on the frequencydomain. The characteristic of such a mapping manner is that, for thedemodulation reference signals multiplexed with the code word [1, −1],mappings thereof on the resource blocks are alternately reverse ondifferent sub-carriers. The result of such a mapping manner is shown inFIG. 7.

FIG. 7 shows a sectional diagram of resource blocks after the Walshcodes with the code length of 2 such as [1, 1] and [1, −1] are used tomultiplex the two layers of demodulation reference signals in the LTE-ARelease-9.

It can be easily seen, by comparing FIG. 5 with FIG. 7, that the peakvalue (A+B) and zero value appear alternately on the different OFDMsymbols when A=B, which reduces the impact of power fluctuation on thepower amplifier.

However, when the number of layers of demodulation reference signals forcode division multiplexing is multiple, the case that the peak valuesand the zero values cannot be distributed evenly as shown in FIG. 4still exists.

SUMMARY OF THE DISCLOSURE

The present disclosure is made in consideration of the above aspects.

According to one aspect of the present disclosure, there is provided acode division multiplexing method based on orthogonal codes ofperforming the code division multiplexing of demodulation referencesignals in multiple layers of resource blocks by using the orthogonalmatrices, the method comprising: changing the order of chips inparticular rows of a first orthogonal matrix to obtain a secondorthogonal matrix with the changed order of chips; and multiplying thechips in respective rows of the second orthogonal matrix by thedemodulation reference signals in corresponding layers of resourceblocks in the time direction to obtain code division multiplexingsignals.

According to another aspect of the present disclosure, there is provideda de-multiplexing method of de-multiplexing code division multiplexingsignals in multiple layers of resource blocks by using orthogonalmatrices, the method comprising: receiving the code divisionmultiplexing signals in the multiple layers of resource blocks;multiplying the chips in respective rows of the orthogonal matrix by thecode division multiplexing signals in corresponding layers of resourceblocks in the time direction to obtain demodulation reference signals,the orthogonal matrix being obtained by changing the order of chips inparticular rows of another orthogonal matrix.

According to a further aspect of the present disclosure, there isprovided a code division multiplexing device based on orthogonal codesfor performing the code division multiplexing of demodulation referencesignals in multiple layers of resource blocks by using orthogonalmatrices, the device comprising: a processing unit which changes theorder of chips in particular rows of a first orthogonal matrix to obtaina second orthogonal matrix with the changed order of chips; and amultiplexing unit which multiplies the chips in respective rows of thesecond orthogonal matrix correspondingly by the demodulation referencesignals in corresponding layers of resource blocks in the time directionto obtain code division multiplexing signals.

According to a still further aspect of the present disclosure, there isprovided a de-multiplexing device for de-multiplexing code divisionmultiplexing signals in multiple layers of resource blocks by usingorthogonal matrices, the device comprising: a receiving unit whichreceives the code division multiplexing signals in the multiple layersof resource blocks; a de-multiplexing unit which multiplies the chips inrespective rows of the orthogonal matrix correspondingly by the codedivision multiplexing signals in corresponding layers of resource blocksin the time direction to obtain the demodulation reference signals, theorthogonal matrix being obtained by changing the order of the chips inparticular rows of another orthogonal matrix.

According to methods and devices of the present disclosure,distributions of the peak values and the zero values can be evened onthe time domain, the forward compatibility of the LTE-A Release-9 can bekept, that is, the first layer and second layer of demodulationreference signals use the mapping manner of Release-9, anddual-orthogonality on the time domain and the frequency domain ispossessed. Thereby, the power fluctuation situation of downlink signalson the time can be improved, the usage efficiency of the power amplifierat the base station side can be improved, and the demodulation referencesignals are robust on the time and frequency selectively fadingchannels.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the present disclosure willbecome more distinct and easier to be understood in a detaileddescription of embodiments of the present disclosure below incombination with attached drawings, in which:

FIG. 1(A) to FIG. 1(D) are diagrams showing that the characteristics ofthe CDM multiplexing and de-multiplexing based on the orthogonal codesare illustrated based on an example of the four-dimensional Walsh codes;

FIG. 2 is a schematic diagram showing that different base stationstransmit multiple data streams to a mobile terminal in a wirelesscommunication system;

FIG. 3 is a diagram showing an example of a resource block constitutinga data stream transmitted to a mobile terminal from a base station in awireless communication system;

FIG. 4 shows an example that the different layers of demodulationreference signals are multiplexed by using an orthogonal matrix;

FIG. 5 shows a sectional diagram of a resource block after two layers ofdemodulation reference signals are multiplexed by using Walsh codes withthe code length of 2 such as [1, 1] and [1, −1];

FIG. 6 shows an actual mapping manner of the code division multiplexingbased on the orthogonal codes in the LTE-A Release-9;

FIG. 7 shows a sectional diagram of resource blocks after the two layersof demodulation reference signals are multiplexed by using Walsh codeswith the code length of 2 such as [1, 1] and [1, −1] in the LTE-ARelease-9;

FIG. 8 shows a case of the demodulation reference signals of a resourceblock in the LTE-A Release-10;

FIG. 9 is a diagram showing that different sub-carriers are reverselymultiplexed, alternately in the time direction;

FIG. 10 is a block diagram showing a code division multiplexing deviceof a wireless communication system according to a first embodiment ofthe present disclosure;

FIG. 11 shows an example that the order of chips of a part of rows in aWalsh matrix is interchanged to produce a non-orthogonal matrix;

FIG. 12 shows an example that the order of chips of a part of rows in aWalsh matrix is shifted cyclically to produce an orthogonal matrix;

FIG. 13 is a another diagram showing that an orthogonal matrix of thecode division multiplexing is obtained according to the presentembodiment;

FIG. 14 is a further diagram showing that an orthogonal matrix of thecode division multiplexing is obtained according to the presentembodiment;

FIG. 15 shows an example of the code division multiplexing based on theorthogonal codes according to an embodiment of the present disclosure;

FIG. 16 shows an example shown on a resource block, in which the cyclicshift is performed for an orthogonal multiplexing manner of the presentdisclosure;

FIG. 17 is a diagram showing the effect of the code divisionmultiplexing manner based on the orthogonal codes of the presentdisclosure;

FIG. 18 shows a code division multiplexing manner of the demodulationreference signals in the fifth to eighth layers of resource blocksaccording to a second embodiment of the present disclosure;

FIG. 19 is a block diagram showing a de-multiplexing device of awireless communication system according to an embodiment of the presentdisclosure;

FIG. 20 is a flowchart of a code division multiplexing method based onthe orthogonal codes according to the present embodiment;

FIG. 21 is a flowchart of a de-multiplexing method according to thepresent embodiment;

FIG. 22 shows an example of a four-dimensional discrete Fouriertransform matrix;

FIG. 23 shows a diagram of an orthogonal codes mapping scheme on thecomplex domain obtained by repeating the method of the first embodimenton the basis of the orthogonal matrix A2 obtained in FIG. 22;

FIG. 24 shows a diagram according to a seventh embodiment of the presentdisclosure;

FIG. 25 is a diagram showing a sub-frame with an extended cyclic prefix;and

FIG. 26 shows an orthogonal codes mapping scheme of the demodulationreference signals as shown in FIG. 25.

DESCRIPTION OF THE EMBODIMENTS

In the following, some specific embodiments of the present disclosurewill be described in detail with reference to attached drawings. If thedetailed description of the related prior art may confuse the mainpoints of the disclosure, the detailed description thereof will not beprovided herewith. In respective embodiments, the identical referencenumerals are used to denote elements or units performing the samefunctions.

FIG. 8 shows a case of the demodulation reference signals of a resourceblock in the LTE-Advanced Release-10 standard.

In the LTE-Advanced Release-10 standard, at most eight layers of datacan be multiplexed on one resource block. As shown in FIG. 8, thedemodulation reference signals in the first to fourth layers of theresource block and the demodulation reference signals in the fifth toeighth layers of the resource block are located on adjacentsub-carriers. When the number of multiplexed layers is over four layers(for example, the number of multiplexed layers is five to eight layers),Walsh sequences with the length of four chips can be used to multiplexthe demodulation reference signals in the first to fourth layers and thedemodulation reference signals in the fifth to eighth layersrespectively. In FIG. 8, it is Frequency Division Multiplexing (FDM)that is performed between the demodulation reference signals in thefirst to the fourth layers and the demodulation reference signals in thefifth to the eighth layers, that is, they are located on differentsub-carriers respectively. The multiplexing manner (mapping manner) forthe demodulation reference signals in the first to the fourth layers mayalso be applied to the multiplexing of the demodulation referencesignals in the fifth to the eighth layers. For a case that the number ofmultiplexed layers is multiple layers in the Release-10, the problemthat distributions of the peak values and the zero values are not evenas described above still exists.

FIG. 9 is a diagram showing that the alternating reverse multiplexing isperformed in the time direction for different sub-carriers.

In FIG. 9, on the right side, there is shown an orthogonal matrix withthe code length of 4, that is, a Walsh orthogonal code matrix A

$\begin{bmatrix}1 & 1 & 1 & 1 \\1 & {- 1} & {- 1} & 1 \\1 & 1 & {- 1} & {- 1} \\1 & {- 1} & {- 1} & 1\end{bmatrix}.$

The matrix contains four rows and four columns of chips, with four chipsof each column corresponding to respective demodulation referencesignals in the first to the fourth layers respectively. According to theresolution of Release-9, the mapping directions of Walsh codes arealternately reverse on the frequency domain.

Specifically, on a first sub-carrier F1, four demodulation referencesignals in the first layer are multiplied by four chips from the firstcolumn to the fourth column in the first row of the orthogonal matrixrespectively, that is, [1, 1, 1, 1], in the positive direction (thedirection from the left to the right as shown here) of the time axis.Four demodulation reference signals in the second layer are multipliedby four chips from the first column to the fourth column in the secondrow of the orthogonal matrix respectively, that is, [1, −1, 1, −1], inthe positive direction of the time axis. Four demodulation referencesignals in the third layer are multiplied by four chips from the firstcolumn to the fourth column in the third row of the orthogonal matrixrespectively, that is, [1, 1, −1, −1], in the positive direction of thetime axis. Four demodulation reference signals in the fourth layer aremultiplied by four chips from the first column to the fourth column inthe fourth row of the orthogonal matrix respectively, that is, [1, −1,−1, 1], in the positive direction of the time axis. At this time, on thefirst sub-carrier F1, the superposed values of the demodulationreference signals located at the same time and frequency positions inthe first to the fourth layers of the resource block are a, b, c, d inthe positive direction of the time axis respectively. If the pre-codingfactors for the demodulation reference signals in the first to thefourth layers of the resource block are the same, it can be found that,on the first sub-carrier, the superposed value “a” located at the OFDMsymbol 901 is the largest peak value, while the superposed valueslocated at other OFDM symbols 902, 903 and 904 are zero.

On a second sub-carrier F2, four demodulation reference signals in thefirst layer are respectively multiplied by four chips from the firstcolumn to the fourth column in the first row of the orthogonal matrix,that is, [1, 1, 1, 1], in the reverse direction (the direction from theright to the left as shown here) of the time axis. Four demodulationreference signals in the second layer are respectively multiplied byfour chips from the first column to the fourth column in the second rowof the orthogonal matrix, that is, [1, −1, 1, −1], in the reversedirection of the time axis. Four demodulation reference signals in thethird layer are respectively multiplied by four chips from the firstcolumn to the fourth column in the third row of the orthogonal matrix,that is, [1, 1, −1, −1], in the reverse direction of the time axis. Fourdemodulation reference signals in the fourth layer are respectivelymultiplied by four chips from the first column to the fourth column inthe fourth row of the orthogonal matrix, that is, [1, −1, −1, 1], in thereverse direction of the time axis. At this time, on the secondsub-carrier F2, the superposed values of the demodulation referencesignals located at the same time and frequency positions in the first tothe fourth layers of the resource block are respectively d, c, b, a inthe positive direction of the time axis. If the pre-coding factors forthe demodulation reference signals in the first to the fourth layers ofthe resource block are the same, it can be found that, on the secondsub-carrier, the superposed value “a” located at the OFDM symbol 904 isthe largest peak value, while the superposed values located at otherOFDM symbols 901, 902 and 903 are zero.

For a third sub-carrier F3, a fourth sub-carrier F4, a fifth sub-carrierF5 and a sixth sub-carrier F6 and the like, the above process on thefirst sub-carrier F1 and the second sub-carrier F2 is repeatedrespectively.

The multiplexing manner as shown in FIG. 9 has two advantages. The oneis that the forward compatibility for the Release-9 is kept: the firstand the second layers of demodulation reference signals keep theproperty of alternating reverse on the frequency domain of theRelease-9. The other is that there are orthogonal properties on the timedomain and on the frequency domain simultaneously, so that thede-multiplexing can be performed through the orthogonal property of thefrequency domain when the orthogonal property of the time domain isdestroyed (selectively fading on the time domain).

However, it can also be seen that, in the above multiplexing (mapping)manner, if the pre-coding factors for the demodulation reference signalsin the first to the fourth layers of the resource block are the same,for any sub-carrier containing the demodulation reference signals, thelargest superposed peak value “a” appears only on the OFDM symbol 901and the OFDM symbol 904, and the superposed values located at other OFDMsymbols 902 and 903 are zero. In such a mapping manner, the effect ofaveraging the peak values and the zero values is not good, and it stillcauses the power fluctuation on the time (between different OFDMsymbols) larger, which disadvantages the usage efficiency of the poweramplifier at the base station side. Therefore, an improvement of themapping manner as shown in FIG. 9 is still needed. The improvement ofthe mapping manner as shown in FIG. 9 should meet the following threeconditions simultaneously: 1. the peak values and zero values can beaveraged on the time domain; 2. the forward compatibility of Release-9can be kept, that is, the first and the second layers of demodulationreference signals use the mapping manner of Release-9; 3. thedual-orthogonality on the time domain and the frequency domain ispossessed.

In the present disclosure, although the first sub-carrier F1 and thesecond sub-carrier F2 and the like are not absolutely adjacentsub-carriers on a resource block, and there are other sub-carrierstransferring data therebetween, they are adjacent in the sub-carriersmodulated with the demodulation reference signals. Thus, they arereferred to as “adjacent sub-carriers” carrying the demodulationreference signals below.

The present disclosure provides orthogonal codes based code divisionmultiplexing method and a code division multiplexing device andde-multiplexing device by using such a method in a wirelesscommunication system. The orthogonal codes based multiplexing methodprovided by the present disclosure has characteristics as follows: thedemodulation reference signals in different layers can use differentmapping manners, that is, they use different orthogonal matrices.However, in FIG. 9, the demodulation reference signals in differentlayers use the same mapping manner on the same sub-carrier, and they usedifferent mapping manners only on different sub-carriers.

First Embodiment

FIG. 10 is a block diagram showing a code division multiplexing deviceof a wireless communication system according to a first embodiment ofthe present disclosure.

As shown in FIG. 10, a code division multiplexing device 1000 accordingto the present disclosure includes a processing unit 1002 and amultiplexing unit 1006 connected with each other.

The code division multiplexing device 1000 according to the presentdisclosure may also include: a Central Processing Unit (CPU) 1010 forexecuting related programs to process various data and to controloperations of the respective units in the device 1000; a Read OnlyMemory (ROM) 1013 for storing various programs required for the CPU 1010to perform various process and control; a Random Access Memory (RAM)1015 for storing intermediate data temporarily produced by the CPU 1010in the procedure of process and control; a Input/Output (I/O) unit 1016for connecting with external devices, transporting various data betweenthe external devices and the code division multiplexing device 1000 andso on. The above processing unit 1002, multiplexing unit 1006, CPU 1010,ROM 1013, RAM 1015, I/O unit 1016, etc. may be connected via a dataand/or command bus 1020, and they transfer signals between one another.

The respective units as described above do not limit the scope of thepresent disclosure. According to one embodiment of the presentdisclosure, the function of either of the processing unit 1002 and themultiplexing unit 1006 may also be realized by functional software incombination with the above CPU 1010, ROM 1013, RAM 1015, I/O unit 1016and the like. And, the functions of the processing unit 1002 and themultiplexing unit 1006 may also be realized by combining them into oneunit.

The code division multiplexing device 1000 of the present disclosureuses an orthogonal matrix such as a Walsh code matrix to perform thecode division multiplexing of the demodulation reference signals inmultiple layers of the resource block. In the code division multiplexingdevice 1000 of the present disclosure, the processing unit 1002 changesthe order of chips of particular rows of an orthogonal matrix (a firstorthogonal matrix) to obtain another orthogonal matrix (a secondorthogonal matrix) with the changed order of the chips. The multiplexingunit 1006 multiplies the chips of respective rows of the secondorthogonal matrix correspondingly by the demodulation reference signalsin the corresponding layers of the resource block in the time directionto obtain the code division multiplexing signals. Here, the particularrows may be all or part of rows of the orthogonal matrix.

It should be noted that the employment of different mapping manners forthe demodulation reference signals in different layers on the samesub-carrier is equivalent to the permuting of particular rows or columnsof a Walsh matrix (orthogonal matrix), but such operation (permuting)sometimes produces a non-orthogonal matrix.

FIG. 11 shows an example that the order of chips in the particular rowsof a Walsh matrix is changed to produce a non-orthogonal matrix.

In FIG. 11, the first column of chips

$\begin{bmatrix}1 \\1\end{bmatrix}\quad$in the last two rows of an orthogonal matrix A are interchanged with thefourth column of chips

$\begin{bmatrix}{- 1} \\1\end{bmatrix}\quad$in the last two rows of the orthogonal matrix to produce a matrix B. Itcan be seen that the matrix B is a non-orthogonal matrix. In the presentdisclosure, such a case should be avoided.

In the present disclosure, the orthogonal property of the demodulationreference signals in different layers on the time domain should beassured at first.

FIG. 12 shows an example that the chips in the particular rows of aWalsh matrix are shifted cyclically to produce an orthogonal matrix.

If the columns of chips in the last two rows of the Walsh matrix A areshifted cyclically, the orthogonal matrices will be produced as shown inFIG. 12. In FIG. 12, the first to fourth columns of chips in the lasttwo rows of the orthogonal matrix A are shifted cyclically by one columnin the positive direction of the time axis (it can be considered as adirection from the left to the right here), a matrix C on the right sidemay be obtained; the first to fourth columns of chips in the last tworows of the matrix C are shifted cyclically by one column in thepositive direction of the time axis, a matrix D on the right side may beobtained; and the first to fourth columns of chips in the last two rowsof the matrix D are shifted cyclically by one column in the positivedirection of the time axis, a matrix E on the right side may beobtained. It can be seen that the matrices C, D and E are all orthogonalmatrices.

Here, it is noted that the orthogonal E equals to a matrix obtained byshifting cyclically the first to fourth columns of chips in the last tworows of the orthogonal matrix A by one column in the reverse directionof the time axis.

According to an embodiment of the present disclosure, the processingunit 1002 may change the order of the chips by shifting cyclically thechips in part of rows of the first orthogonal matrix (the orthogonalmatrix A) in the positive or reverse direction of the time axis toobtain the second orthogonal matrix (the orthogonal matrices C, D, E).And, the multiplexing unit 1006 multiplies the demodulation referencesignals in the adjacent sub-carriers in respective layers of theresource block by the chips of the first to the last columns of thesecond orthogonal matrix alternately reverse in the time direction.

The first orthogonal matrix or the second orthogonal matrix according tothe present disclosure is not limited to the above situation, and thefirst orthogonal matrix may be any one of the following orthogonalmatrices:

$\begin{bmatrix}1 & 1 & 1 & 1 \\1 & {- 1} & 1 & {- 1} \\1 & 1 & {- 1} & {- 1} \\1 & {- 1} & {- 1} & 1\end{bmatrix},\begin{bmatrix}1 & 1 & 1 & 1 \\1 & {- 1} & 1 & {- 1} \\{- 1} & 1 & 1 & {- 1} \\1 & 1 & {- 1} & {- 1}\end{bmatrix},{\quad{\begin{bmatrix}1 & 1 & 1 & 1 \\1 & {- 1} & 1 & {- 1} \\{- 1} & {- 1} & 1 & 1 \\{- 1} & 1 & 1 & {- 1}\end{bmatrix},{\quad{\begin{bmatrix}1 & 1 & 1 & 1 \\1 & {- 1} & 1 & {- 1} \\1 & {- 1} & {- 1} & 1 \\{- 1} & {- 1} & 1 & 1\end{bmatrix},}}}}$so the second orthogonal matrix can be other matrix except for the firstorthogonal matrix.

FIG. 13 is another diagram showing an orthogonal matrix for the codedivision multiplexing according to the present embodiment.

According to an embodiment of the present disclosure, the order of thechips may also be changed by multiplying a part of rows of the firstorthogonal matrix by nonzero numbers and shifting cyclically the chipsin the respective rows in the positive or reverse direction of the timeaxis. As shown in FIG. 13, the matrix A (the first orthogonal matrix) isa classic Walsh matrix, and the second row of the matrix A is multipliedby (−1) to obtain a matrix A1 which is an orthogonal matrix. The columnsof the matrix A1 are shifted cyclically by one bit toward the right (inthe positive direction of the time axis) to obtain a matrix A2 (thesecond orthogonal matrix). The matrix A2 is the orthogonal matrix C asshown in FIG. 12. According to the same manner, the columns of thematrix A1 are shifted cyclically by one bit toward the left (in thereverse direction of the time axis), and the orthogonal matrix E asshown in FIG. 12 (the second orthogonal matrix) is obtained.

FIG. 14 is a further diagram showing an orthogonal matrix for the codedivision multiplexing according to the present embodiment.

As shown in FIG. 14, the matrix A1 obtained by multiplying a certain rowor certain rows of the matrix A (the first orthogonal matrix) by nonzeronumbers (real numbers or complex numbers), for example, a, b, c shown inFIG. 14 (which may be any nonzero numbers) is still an orthogonalmatrix. The matrix A1 is performed with the row or column interchange toobtain the A2 (the second orthogonal matrix). In FIG. 13 and FIG. 14,although the change from A1 to A2 is through the cyclic shift ofcolumns, any interchange and shift of the rows or columns of the A1produces an orthogonal matrix because the A1 itself is an orthogonalmatrix.

According to an embodiment of the present disclosure, the processingunit 1002 may also change the order of the chips by multiplying a partof rows of the first orthogonal matrix (the orthogonal matrix A) bynonzero numbers and then shifting cyclically the chips in the respectiverows in the positive or reverse direction of the time axis to obtain thesecond orthogonal matrix (the orthogonal matrices C, D, E). And, themultiplexing unit 1006 multiplies the demodulation reference signals inthe adjacent sub-carriers in respective layers of the resource block bythe chips in the first to the last columns of the second orthogonalmatrix alternately reverse in the time direction.

It can be seen from the above FIG. 12 to FIG. 14 that any matrix of forexample A, C, D, E and the like as described above may be taken as abasic matrix (the first orthogonal matrix), and the chips in theparticular rows of the matrix is shifted cyclically to obtain the otherorthogonal matrices.

According to an embodiment of the present disclosure, if the orthogonalmatrix includes N rows×N columns of chips, and the multiple layers ofresource block include N layers of resource block (the demodulationreference signals in the N layers of resource block are located at thesame predetermined time and frequency position), the multiplexing unit1006 may multiply the respective columns of chips in the n-th row of thesecond orthogonal matrix by the demodulation reference signals in then-th layer of the resource block correspondingly in the time direction.Here, n=1, . . . , N, and N may be a natural number.

FIG. 15 shows an example of the code division multiplexing based on theorthogonal codes according to an embodiment of the present disclosure.

In FIG. 15, it is shown a case of N=4, that is, the orthogonal matrix isan orthogonal matrix of 4×4 orders, and the multiple layers of theresource block include 4 layers of resource block.

Here, a first resource block RB1 is taken as an example. For thedemodulation reference signals in the first to the fourth layers of theresource block on the first sub-carrier F1, the chips in the last tworows of the orthogonal matrix A are shifted cyclically by one column inthe positive direction of the time axis to obtain the orthogonal matrixC, and the demodulation reference signals in the first to the fourthlayers of the resource block on the first sub-carrier F1 arerespectively multiplied by the first to the fourth columns of chips ofthe orthogonal matrix C in the positive direction of the time axis (thedirection of T1→T2→T3→T4).

Specifically, for the first sub-carrier F1, the demodulation referencesignals in the first layer of the resource block are respectivelymultiplied by the first to the fourth columns of chips in the first rowof the orthogonal matrix C, that is [1, 1, 1, 1], in the positivedirection of the time axis. The demodulation reference signals in thesecond layer of the resource block are respectively multiplied by thefirst to the fourth columns of chips in the second row of the orthogonalmatrix C, that is [1, −1, 1, −1], in the positive direction of the timeaxis. The demodulation reference signals in the third layer of theresource block are respectively multiplied by the first to the fourthcolumns of chips in the third row of the orthogonal matrix C, that is[−1, 1, 1, −1], in the positive direction of the time axis. Thedemodulation reference signals in the fourth layer of the resource blockare respectively multiplied by the first to the fourth columns of chipsin the fourth row of the orthogonal matrix C, that is [1, 1, −1, −1], inthe positive direction of the time axis.

For the demodulation reference signals in the first to the fourth layersof the resource block on the second sub-carrier F2, the chips in thelast two rows of the orthogonal matrix A are shifted cyclically by onecolumn in the positive direction of the time axis to obtain theorthogonal matrix C, and the demodulation reference signals in the firstto the fourth layers of the resource block on the second sub-carrier F2are respectively multiplied by the first to the fourth columns of chipsof the orthogonal matrix C in the reverse direction of the time axis(the direction of T4→T3→T2→T1).

Specifically, for the second sub-carrier F2, the demodulation referencesignals in the first layer of the resource block are respectivelymultiplied by the first to the fourth columns of chips in the first rowof the orthogonal matrix C, that is [1, 1, 1, 1], in the reversedirection of the time axis. The demodulation reference signals in thesecond layer of the resource block are respectively multiplied by thefirst to the fourth columns of chips in the second row of the orthogonalmatrix C, that is [1, −1, 1, −1], in the reverse direction of the timeaxis. The demodulation reference signals in the third layer of theresource block are respectively multiplied by the first to the fourthcolumns of chips in the third row of the orthogonal matrix C, that is[−1, 1, 1, −1], in the reverse direction of the time axis. Thedemodulation reference signals in the fourth layer of the resource blockare respectively multiplied by the first to the fourth columns of chipsin the fourth row of the orthogonal matrix C, that is [1, 1, −1, −1], inthe reverse direction of the time axis. Here, the multiplication of thedemodulation reference signals in the respective layers on the secondsub-carrier by the first to the fourth columns of chips of theorthogonal matrix C in the reverse direction of the time axis isequivalent to the multiplication of the demodulation reference signalsin the respective layers on the second sub-carrier by the first to thefourth columns of chips of an orthogonal matrix C′ in the positivedirection of the time axis. The orthogonal matrix C′ equals to anorthogonal matrix obtained by arranging the first to the fourth columnsof chips of the orthogonal matrix C reversely.

For the demodulation reference signals in the first to the fourth layersof the resource block on the third sub-carrier F3, the same operationsas those of the demodulation reference signals in the first to thefourth layers of the resource block on the first sub-carrier F1 arerepeated.

According to an embodiment of the present disclosure, the following codedivision multiplexing manner may also be employed.

Here, a second resource block RB2 is taken as an example. For thedemodulation reference signals in the first to the fourth layers of theresource block on the first sub-carrier F1, the chips in the last tworows of the orthogonal matrix A are shifted cyclically by one column inthe reverse direction of the time axis to obtain the orthogonal matrixE, and the demodulation reference signals in the first to the fourthlayers of the resource block on the first sub-carrier F1 arerespectively multiplied by the first to the fourth columns of chips ofthe orthogonal matrix E in the reverse direction of the time axis (thedirection of T4→T3→T2→T1).

Specifically, for the first sub-carrier F1, the demodulation referencesignals in the first layer of the resource block are respectivelymultiplied by the first to the fourth columns of chips in the first rowof the orthogonal matrix E, [1, 1, 1, 1], in the reverse direction ofthe time axis. The demodulation reference signals in the second layer ofthe resource block are respectively multiplied by the first to thefourth columns of chips in the second row of the orthogonal matrix E,[1, −1, 1, −1], in the reverse direction of the time axis. Thedemodulation reference signals in the third layer of the resource blockare respectively multiplied by the first to the fourth columns of chipsin the third row of the orthogonal matrix E, [1, −1, −1, 1], in thereverse direction of the time axis. The demodulation reference signalsin the fourth layer of the resource block are respectively multiplied bythe first to the fourth columns of chips in the fourth row of theorthogonal matrix E, [−1, −1, 1, 1], in the reverse direction of thetime axis. Here, the multiplication of the demodulation referencesignals in respective layers on the first sub-carrier by the first tothe fourth columns of chips of the orthogonal matrix E in the reversedirection of the time axis is equivalent to the multiplication of thedemodulation reference signals in respective layers on the firstsub-carrier by the first to the fourth columns of chips of an orthogonalmatrix E′ in the positive direction of the time axis. The orthogonalmatrix E′ equals to an orthogonal matrix obtained by arranging the firstto the fourth columns of chips of the orthogonal matrix E reversely.

For the demodulation reference signals in the first to the fourth layersof the resource block on the second sub-carrier F2, the chips in thelast two rows of the orthogonal matrix A are shifted cyclically by onecolumn in the reverse direction of the time axis to obtain theorthogonal matrix E, and the demodulation reference signals in the firstto the fourth layers of the resource block on the second sub-carrier F2are respectively multiplied by the first to the fourth columns of chipsof the orthogonal matrix E in the positive direction of the time axis(the direction of T1→T2→T3→T4).

Specifically, for the second sub-carrier F2, the demodulation referencesignals in the first layer of the resource block are respectivelymultiplied by the first to the fourth columns of chips in the first rowof the orthogonal matrix E, [1, 1, 1, 1], in the positive direction ofthe time axis. The demodulation reference signals in the second layer ofthe resource block are respectively multiplied by the first to thefourth columns of chips in the second row of the orthogonal matrix E,[1, −1, 1, −1], in the positive direction of the time axis. Thedemodulation reference signals in the third layer of the resource blockare respectively multiplied by the first to the fourth columns of chipsin the third row of the orthogonal matrix E, [1, −1, −1, 1], in thepositive direction of the time axis. The demodulation reference signalsin the fourth layer of the resource block are respectively multiplied bythe first to the fourth columns of chips in the fourth row of theorthogonal matrix E, [−1, −1, 1, 1], in the positive direction of thetime axis.

For the demodulation reference signals in the first to the fourth layersof the resource block on the third sub-carrier F3, the same operationsas those of the demodulation reference signals in the first to thefourth layers of the resource block on the first sub-carrier F1 arerepeated.

FIG. 16 shows an example shown on a resource block, in which the cyclicshift is performed for an orthogonal multiplexing manner of the presentdisclosure.

In FIG. 16, for the demodulation reference signals in the first and thesecond layers of the resource block, the mapping is performed by usingan orthogonal matrix X, and it reverses alternately on adjacentsub-carriers such as the first sub-carrier F1, the second sub-carrierF2, the third sub-carrier F3, the fourth sub-carrier F4, the fifthsub-carrier F5, the sixth sub-carrier F6 and the like, which isconsistent with the manner in the Release-9. For the demodulationreference signals in the third and the fourth layers of the resourceblock, the mapping is performed by cyclically shifting the respectivecolumns of chips of an orthogonal matrix Y. Here, the orthogonal matrixX is composed of the first and the second rows of chips of theorthogonal matrix A shown in FIG. 11 and FIG. 12, and the orthogonalmatrix Y is composed of the third and the fourth rows of chips of theorthogonal matrix A shown in FIG. 11 and FIG. 12.

Specifically, for the first sub-carrier F1, the mapping manner of a, b,c, d for the demodulation reference signals in the first layer and thesecond layer is cyclically shifted by one OFDM symbol in the positivedirection of the time axis, and the mapping manner of d, a, b, c for thedemodulation reference signals in the third layer and the fourth layeris obtained.

For the second sub-carrier F2, the mapping manner of d, a, b, c for thedemodulation reference signals in the first layer and the second layeris cyclically shifted by one OFDM symbol in the reverse direction of thetime axis, and the mapping manner of c, b, a, d for the demodulationreference signals in the third layer and the fourth layer is obtained.

For the third sub-carrier F3, the mapping manner of a, b, c, d for thedemodulation reference signals in the first layer and the second layeris cyclically shifted by one OFDM symbol in the positive direction ofthe time axis, and the mapping manner of d, a, b, c for the demodulationreference signals in the third layer and the fourth layer is obtained.

For the fourth sub-carrier F4, the mapping manner of d, c, b, a for thedemodulation reference signals in the first layer and the second layeris cyclically shifted by one OFDM symbol in the positive direction ofthe time axis, and the mapping manner of a, d, c, b for the demodulationreference signals in the third layer and the fourth layer is obtained.

For the fifth sub-carrier F5, the mapping manner of a, b, c, d for thedemodulation reference signals in the first layer and the second layeris cyclically shifted by one OFDM symbol in the reverse direction of thetime axis, and the mapping manner of b, c, d, a for the demodulationreference signals in the third layer and the fourth layer is obtained.

For the sixth sub-carrier F6, the mapping manner of d, c, b, a for thedemodulation reference signals in the first layer and the second layeris cyclically shifted by one OFDM symbol in the positive direction ofthe time axis, and the mapping manner of a, d, c, b for the demodulationreference signals in the third layer and the fourth layer is obtained.

The above cyclic shift of the mapping manners of the demodulationreference signals in different layers on different sub-carriers shown inthe resource block equals to that, as shown in FIG. 15, the chips in thethird row and the fourth row of the orthogonal matrix A are cyclicallyshifted in the time direction, that is, the chips in the last twocolumns of the orthogonal matrix A are cyclically shifted by one columnin the positive or reverse direction of the time axis to obtain theorthogonal matrices C and E, and the demodulation reference signals inthe first to the fourth layers of the resource block on the adjacentsub-carriers are respectively multiplied by the chips in the first tothe fourth columns of the orthogonal matrices C and E in the positive orreverse direction of the time axis.

According to an embodiment of the present disclosure, the mapping mannerof the first and the second layers is consistent with the mapping mannerof the Release-9, thus the forward compatibility is assured. On eachsub-carrier, there is correspondence between the mapping manner of thefirst and second layers and the mapping manner of the third and fourthlayers. In FIG. 16, on the first sub-carrier, the mapping manner for thedemodulation reference signals in the first and the second layers arecyclically shifted by one OFDM symbol in the positive direction of thetime axis, and the mapping manner for the demodulation reference signalsin the third and the fourth layers on this sub-carrier is obtained. Inthe next sub-carrier, the mapping manner for the first and the secondlayers is shifted by one OFDM symbol in the reverse direction, and themapping manner for the third and the fourth layers can be obtained. Bythe same way, the mapping manners of the third and the fourth layers inthe remaining sub-carriers can be obtained. Since the demodulationreference signals corresponding to the first, second, third and fourthlayers are multiplexed on the same time and frequency resource, suchdifferent mapping manners for the demodulation reference signals in thefirst, second, third and fourth layers is equivalent to that the chipsin the last two rows of a Walsh matrix (an orthogonal matrix) arecyclically shifted as shown in FIG. 15. The orthogonal property on thetime domain and the frequency domain of the mapping manners of thepresent embodiment may be shown in FIG. 17.

FIG. 17 is a diagram shown the effect of the code division multiplexingmanner based on the orthogonal codes of the present disclosure.

In FIG. 17, the equalizing function for power peak values of the presentembodiment is shown. It is assumed that real values for the demodulationreference signals in different layers (the first to fourth layers) areA, B, C and D (A, B, C, D may be any complex numbers) respectively, andin FIG. 17, the different shadows represent possible different powervalues. Each shadow is assigned to four OFDM symbols in the mappingmanners provided by the present embodiment. It can be distinctlyillustrated from the quantitative analysis below that the mannersprovided by the present embodiment is able to resolve the equalizingproblem of the power peak values. By superposing the powers of thedemodulation reference signals on the six sub-carriers in the firstresource block RB1 and the second resource block RB2 in FIG. 17, thetotal power of each OFDM symbol (T1˜T4) may be obtained: the accumulatedpowers on T1 and T2 are identical, i.e.6(|A|²+|B|²+|C|²+|D|²)+2(AD*+DA*)−2(BC*+CB*); the accumulated powers onT3 and T4 are identical, i.e.6(|A|²+|B|²+|C|²+|D|²)−2(AD*+DA*)+2(BC*+CB*). In the above calculation,|A| represents the modulus value of the complex number A, and A*represents the conjugate of the complex number A. It is assumed that byusing the method of alternately reversing on the time domain as shown inFIG. 9, the power accumulation values on such four OFDM symbols of T1˜T4can be obtained by calculation similarly: the accumulated powers on T1and T4 are identical, i.e. 6(|A|²+|B|²+|C|²+|D|²)+6(AD*+DA*)+6(BC*+CB*);the accumulated powers on T2 and T3 are identical, i.e.6(|A|²+|B|²+|C|²+|D|²)−6(AD*+DA*)−6(BC*+CB*). In the above poweraccumulation values, the term of 6(|A|²+|B|²+|C|²+|D|²) is in common, sothe power fluctuation is mainly dependent on the cross-multiplicationterms of A, B, C, D. In the calculation of the present embodiment, thefactors before the corresponding cross-multiplication terms are 2; incontrast, in the calculation of the method as shown in FIG. 9, thefactors before the corresponding cross-multiplication terms are 6.Consequently, the present embodiment can effectively average the powerof peak values. Finally, the efficiency of the present embodiment mayalso be verified by using a simple example. It is assumed that A=B=C=D.It can be obtained from the above calculation that the accumulated poweron T1˜T4 are all 6(|A|²+|B|²+|C|²+|D|²) in the present embodiment,however, in the method as shown in FIG. 9, the accumulated power on T1and T4 are 6(|A|²+|B|²+|C|²+|D|²), and the accumulated power on T2 andT3 are both zero.

Therefore, the present embodiment can effectively eliminate a problem ofjitter on the time domain of the transmission power of a base station;meanwhile, the mapping method possesses the dual-orthogonality on thetime domain and the frequency domain, and it can keep the forwardcompatibility of 3GPP LTE-Advanced Release-9 standard, and especiallyimproves the usage efficiency of the power amplifier at the base stationside.

The manner of the code division multiplexing of the demodulationreference signals in N layers (the first to fourth layers) of a resourceblock is described above. According to an embodiment of the presentdisclosure, there may also be included further N layers of the resourceblock, the demodulation reference signals in which are located at thepredetermined time and frequency positions different from thedemodulation reference signals in the N layers of the resource block asdescribed above.

The manner of the code division multiplexing based on the orthogonalcodes of the demodulation reference signals in the fifth to the eighthlayers of the resource block may be performed by employing the sameprocessing manner as the first to the fourth layers of the resourceblock.

Second Embodiment

FIG. 18 shows a code division multiplexing manner of the demodulationreference signals in the five to eight layers of a resource blockaccording to a second embodiment of the present disclosure.

In the present embodiment, the demodulation reference signals in theeight layers of data (resource block) are distributed on two adjacentsub-carriers, as shown in FIG. 8. The first embodiment aims to a casethat four layers of the demodulation reference signals are assigned onone sub-carrier, which does not relate to the case of the demodulationreference signals assigned on two adjacent sub-carriers. When themapping manner in the fifth to the eighth layers of the demodulationreference signals is designed, one simple method is to use repeatedlythe mapping manner of the first to the fourth layers, such as the methodin the first embodiment. However, in fact, the reference signals in thefifth to the eighth layers may also use a mapping manner different fromthe first to the fourth layers, and the present embodiment gives oneexample different from the mapping manner of the first to the fourthlayers. According to the present embodiment, the demodulation referencesignals in the fifth to the eighth layers and the demodulation referencesignals in the first to the fourth layers employ different mappingmanners. In FIG. 18, only the mapping manner of the fifth to the eighthlayers is given, and the mapping manner of the first to the fourthlayers is the same as the first embodiment.

As shown in FIG. 18, the demodulation reference signals in the fifth andthe sixth layers of the resource block are mapped by using an orthogonalmatrix X, and it reverses alternately on the adjacent sub-carriersmodulated with the demodulation reference signals such as the firstsub-carrier F1, the second sub-carrier F2, the third sub-carrier F3, thefourth sub-carrier F4, the fifth sub-carrier F5, the sixth sub-carrierF6 and the like, which is consistent with the manner in Release-9. Forthe demodulation reference signals in the seventh and the eighth layersof the resource block, the mapping is performed by cyclically shiftingthe respective columns of chips of an orthogonal matrix Y. Here, theorthogonal matrix X is composed of the first and second rows of chips ofthe orthogonal matrix A as shown in FIG. 11 and FIG. 12, and theorthogonal matrix Y is composed of the third and fourth rows of chips ofthe orthogonal matrix A as shown in FIG. 11 and FIG. 12.

Specifically, for the first sub-carrier F1, the mapping manner of a, b,c, d for the demodulation reference signals in the fifth layer and thesixth layer is cyclically shifted by one OFDM symbol in the reversedirection of the time axis, and the mapping manner of b, c, d, a for thedemodulation reference signals in the seven layer and the eighth layeris obtained.

For the second sub-carrier F2, the mapping manner of d, c, b, a for thedemodulation reference signals in the fifth layer and the sixth layer iscyclically shifted by one OFDM symbol in the positive direction of thetime axis, and the mapping manner of a, d, c, b for the demodulationreference signals in the seventh layer and the eighth layer is obtained.

For the third sub-carrier F3, the mapping manner of a, b, c, d for thedemodulation reference signals in the fifth layer and the sixth layer iscyclically shifted by one OFDM symbol in the reverse direction of thetime axis, and the mapping manner of b, c, d, a for the demodulationreference signals in the seventh layer and the eighth layer is obtained.

For the fourth sub-carrier F4, the mapping manner of d, c, b, a for thedemodulation reference signals in the fifth layer and the sixth layer iscyclically shifted by one OFDM symbol in the reverse direction of thetime axis, and the mapping manner of c, b, a, d for the demodulationreference signals in the seventh layer and the eighth layer is obtained.

For the fifth sub-carrier F5, the mapping manner of a, b, c, d for thedemodulation reference signals in the fifth layer and the sixth layer iscyclically shifted by one OFDM symbol in the positive direction of thetime axis, and the mapping manner of d, a, b, c for the demodulationreference signals in the seventh layer and the eighth layer is obtained.

For the sixth sub-carrier F6, the mapping manner of d, c, b, a for thedemodulation reference signals in the fifth layer and the sixth layer iscyclically shifted by one OFDM symbol in the reverse direction of thetime axis, and the mapping manner of c, b, a, d for the demodulationreference signals in the seventh layer and the eighth layer is obtained.

The above cyclic shift of the mapping manners of the demodulationreference signals in different layers on different sub-carriers as shownin the fifth to the eighth layers of the resource block is equivalent tothe following manner.

Here, a first resource block RB1 is taken as an example. For thedemodulation reference signals in the fifth to the eighth layers of theresource block on the first sub-carrier F1, the chips in the last tworows of the orthogonal matrix A are shifted cyclically by one column inthe reverse direction of the time axis to obtain the orthogonal matrixE, and the demodulation reference signals in the fifth to the eighthlayers of the resource block on the first sub-carrier F1 arerespectively multiplied by the first to the fourth columns of chips ofthe orthogonal matrix E in the positive direction of the time axis (thedirection of T1→T2→T3→T4, that is, a direction from the left to theright).

Specifically, for the first sub-carrier F1, the demodulation referencesignals in the fifth layer of the resource block are respectivelymultiplied by the first to the fourth columns of chips in the first rowof the orthogonal matrix E, [1, 1, 1, 1], in the positive direction ofthe time axis. The demodulation reference signals in the sixth layer ofthe resource block are respectively multiplied by the first to thefourth columns of chips in the second row of the orthogonal matrix E,[1, −1, 1, −1], in the positive direction of the time axis. Thedemodulation reference signals in the seventh layer of the resourceblock are respectively multiplied by the first to the fourth columns ofchips in the third row of the orthogonal matrix E, [1, −1, −1, 1], inthe positive direction of the time axis. The demodulation referencesignals in the eighth layer of the resource block are respectivelymultiplied by the first to the fourth columns of chips in the fourth rowof the orthogonal matrix E, [−1, −1, 1, 1], in the positive direction ofthe time axis.

For the demodulation reference signals in the fifth to the eighth layersof the resource block on the second sub-carrier F2, the chips in thelast two rows of the orthogonal matrix A are shifted cyclically by onecolumn in the reverse direction of the time axis to obtain theorthogonal matrix E, and the demodulation reference signals in the fifthto the eighth layers of the resource block on the second sub-carrier F2are respectively multiplied by the first to the fourth columns of chipsof the orthogonal matrix E in the reverse direction of the time axis(the direction of T4→T3→T2→T1, that is, a direction from the right tothe left). Specifically, for the second sub-carrier F2, the demodulationreference signals in the fifth layer of the resource block arerespectively multiplied by the first to the fourth columns of chips inthe first row of the orthogonal matrix E, [1, 1, 1, 1], in the reversedirection of the time axis, the demodulation reference signals in thesixth layer of the resource block are respectively multiplied by thefirst to the fourth columns of chips in the second row of the orthogonalmatrix E, [1, −1, 1, −1], in the reverse direction of the time axis, thedemodulation reference signals in the seventh layer of the resourceblock are respectively multiplied by the first to the fourth columns ofchips in the third row of the orthogonal matrix E, [1, −1, −1, 1], inthe reverse direction of the time axis, and the demodulation referencesignals in the eighth layer of the resource block are respectivelymultiplied by the first to the fourth columns of chips in the fourth rowof the orthogonal matrix E, [−1, −1, 1, 1], in the reverse direction ofthe time axis. Here, the multiplication of the demodulation referencesignals in respective layers on the second sub-carrier by the first tothe fourth columns of chips of the orthogonal matrix E in the reversedirection of the time axis is equivalent to the multiplication of thedemodulation reference signals in respective layers on the secondsub-carrier by the first to the fourth columns of chips of an orthogonalmatrix E′ in the positive direction of the time axis. The orthogonalmatrix E′ equals to an orthogonal matrix obtained by arranging the firstto the fourth columns of chips of the orthogonal matrix E reversely.

For the demodulation reference signals in the fifth to the eighth layersof the resource block on the third sub-carrier F3, the same operationsas those of the demodulation reference signals in the fifth to theeighth layers of the resource block on the first sub-carrier F1 arerepeated.

According to an embodiment of the present disclosure, the following codedivision multiplexing manner may also be employed.

Here, a second resource block RB2 is taken as an example. For thedemodulation reference signals in the fifth to the eighth layers of theresource block on the first sub-carrier F1, the chips in the last tworows of the orthogonal matrix A are shifted cyclically by one column inthe positive direction of the time axis to obtain the orthogonal matrixC, and the demodulation reference signals in the fifth to the eighthlayers of the resource block on the first sub-carrier F1 arerespectively multiplied by the first to the fourth columns of chips ofthe orthogonal matrix C in the reverse direction of the time axis (thedirection of T4→T3→T2→T1).

Specifically, for the first sub-carrier F1, the demodulation referencesignals in the fifth layer of the resource block are respectivelymultiplied by the first to the fourth columns of chips [1, 1, 1, 1] inthe first row of the orthogonal matrix C in the reverse direction of thetime axis, the demodulation reference signals in the sixth layer of theresource block are respectively multiplied by the first to the fourthcolumns of chips [1, −1, 1, −1] in the second row of the orthogonalmatrix C in the reverse direction of the time axis, the demodulationreference signals in the seventh layer of the resource block arerespectively multiplied by the first to the fourth columns of chips [−1,1, 1, −1] in the third row of the orthogonal matrix C in the reversedirection of the time axis, and the demodulation reference signals inthe eighth layer of the resource block are respectively multiplied bythe first to the fourth columns of chips [1, 1, −1, −1] in the fourthrow of the orthogonal matrix C in the reverse direction of the timeaxis. Here, the multiplication of the demodulation reference signals inrespective layers on the first sub-carrier by the first to the fourthcolumns of chips of the orthogonal matrix C in the reverse direction ofthe time axis is equivalent to the multiplication of the demodulationreference signals in respective layers on the first sub-carrier by thefirst to the fourth columns of chips of an orthogonal matrix C′ in thepositive direction of the time axis. The orthogonal matrix C′ equals toan orthogonal matrix obtained by arranging the first to the fourthcolumns of chips of the orthogonal matrix C reversely.

For the demodulation reference signals in the fifth to the eighth layersof the resource block on the second sub-carrier F2, the chips in thelast two rows of the orthogonal matrix A are shifted cyclically by onecolumn in the positive direction of the time axis to obtain theorthogonal matrix C, and the demodulation reference signals in the fifthto the eighth layers of the resource block on the second sub-carrier F2are respectively multiplied by the first to the fourth columns of chipsof the orthogonal matrix C in the positive direction of the time axis(the direction of T1→T2→T3→T4).

Specifically, for the second sub-carrier F2, the demodulation referencesignals in the fifth layer of the resource block are respectivelymultiplied by the first to the fourth columns of chips [1, 1, 1, 1] inthe first row of the orthogonal matrix C in the positive direction ofthe time axis, the demodulation reference signals in the sixth layer ofthe resource block are respectively multiplied by the first to thefourth columns of chips [1, −1, 1, −1] in the second row of theorthogonal matrix C in the positive direction of the time axis, thedemodulation reference signals in the seventh layer of the resourceblock are respectively multiplied by the first to the fourth columns ofchips [−1, 1, 1, −1] in the third row of the orthogonal matrix C in thepositive direction of the time axis, and the demodulation referencesignals in the eighth layer of the resource block are respectivelymultiplied by the first to the fourth columns of chips [1, 1, −1, −1] inthe fourth row of the orthogonal matrix C in the positive direction ofthe time axis.

For the demodulation reference signals in the fifth to the eighth layersof the resource block on the third sub-carrier F3, the same operationsas those of the demodulation reference signals in the fifth to theeighth layers of the resource block on the first sub-carrier F1 arerepeated.

According to implementation of the present embodiment, a problem ofjitter on the time domain of the transmission power of a base stationcan be effectively eliminated; meanwhile, the mapping method possessesthe dual-orthogonality on the time domain and the frequency domain, andthe forward compatibility of 3GPP LTE-Advanced Release-9 standard can bekept, and especially the usage efficiency of the power amplifier at thebase station side is improved.

According to one embodiment of the present disclosure, the method in thefirst embodiment may also be used for the demodulation reference signalsin the fifth to the eighth layers; meanwhile, the method in the presentembodiment may be used for the demodulation reference signals in thefirst to the fourth layers.

In the present embodiment, there is correspondence between theorthogonal matrices used for mapping on each sub-carrier and theorthogonal matrices in the first embodiment. For example, in the firstembodiment, the orthogonal matrix used on the sub-carrier F1 of the RB1is the orthogonal matrix C obtained by cyclically shifting the chips inthe last two rows of the orthogonal matrix A by one column in thepositive direction of the time axis; and in the second embodiment, theorthogonal matrix used on the sub-carrier F1 of the RB1 (adjacent to thesub-carrier F1 of the first embodiment) is the orthogonal matrix Eobtained by cyclically shifting the chips in the last two rows of theorthogonal matrix A by one column in the reverse direction of the timeaxis. In the subsequent sub-carriers, such relationship is followed.

Third Embodiment

FIG. 19 is a block diagram showing a de-multiplexing device of awireless communication system according to an embodiment of the presentdisclosure.

As shown in FIG. 19, a de-multiplexing device 1900 according to thepresent disclosure includes a de-multiplexing unit 1902 and a receivingunit 1906 connected with each other.

The de-multiplexing device 1900 according to the present disclosure mayalso include: a Central Processing Unit (CPU) 1910 for executing relatedprograms to process various data and to control operations of respectiveunits in the device 1900; a Read Only Memory (ROM) 1913 for storingvarious programs required for the CPU 1910 to perform various processand control; a Random Access Memory (RAM) 1915 for storing intermediatedata temporarily produced by the CPU 1910 in the procedure of processand control; a Input/Output (I/O) unit 1916 for connecting with externaldevices, transporting various data between the external devices and thede-multiplexing device 1900 and so on. The above de-multiplexing unit1902, receiving unit 1906, CPU 1910, ROM 1913, RAM 1915, I/O unit 1916,etc. may be connected via a data and/or command bus 1920, and theytransfer signals between one another.

The respective units as described above do not limit the scope of thepresent disclosure. According to an embodiment of the presentdisclosure, the function of either of the de-multiplexing unit 1902 andthe receiving unit 1906 may also be realized by functional software incombination with the above CPU 1910, ROM 1913, RAM 1915, I/O unit 1916and the like. And, the functions of the de-multiplexing unit 1902 andthe receiving unit 1906 may also be realized by combining them into oneunit.

The de-multiplexing device 1900 of the present disclosure uses anorthogonal matrix to perform de-multiplexing of the code divisionmultiplexing signals in multiple layers of the resource block. In thede-multiplexing device 1900, the receiving unit 1906 receives the codedivision multiplexing signals in the multiple layers of the resourceblock. The de-multiplexing unit 1902 multiplies the chips in respectiverows of the orthogonal matrix correspondingly by the code divisionmultiplexing signals in the corresponding layers of the resource blockto obtain the demodulation reference signals. According to the presentembodiment, the orthogonal matrix may be an orthogonal matrix obtainedby changing the order of chips in particular rows of another orthogonalmatrix. In the matrix obtained by changing the order of chips in a partof rows, the original orthogonal properties between the respective rowsand between the respective columns of the original orthogonal matrix arekept simultaneously.

According to an embodiment of the present disclosure, in the aboveorthogonal matrix, it may change the order of chips by cyclicallyshifting the chips in a part of rows of another orthogonal matrix in thepositive or reverse direction of the time axis, or by multiplying a partof rows of another orthogonal matrix by nonzero numbers and cyclicallyshifting the chips in the respective rows in the positive or reversedirection of the time axis. The de-multiplexing unit 1902 may multiplythe code division multiplexing signals on the adjacent sub-carriers inthe respective layers of the resource block by the chips in the firstcolumn to the last column of the orthogonal matrix with the order ofchips changed alternately reverse in the time direction.

Specifically, for example, the first sub-carrier F1 of the firstresource block RB1 shown in FIG. 15 is taken as an example. When thereceiving unit 1906 receives the demodulation reference signals such asS1, S2, S3, S4 on the first sub-carrier F1 of the first resource blockRB1, which are coded and multiplexed by using the manner of the firstembodiment or the second embodiment of the present disclosure, thede-multiplexing unit 1902 multiplies the received code divisionmultiplexing signals S1, S2, S3, S4 by the corresponding rows of theorthogonal matrix C after the cyclic shift, thereby the originaldemodulation reference signals in the respective layers of the resourceblock can be obtained.

According to implementation of the present embodiment, a problem ofjitter on the time domain of the transmission power of a base stationcan be effectively eliminated; meanwhile, the mapping method possessesthe dual-orthogonality on the time domain and the frequency domain, andthe forward compatibility of 3GPP LTE-Advanced Release-9 standard can bekept, and especially the usage efficiency of the power amplifier at thebase station side is improved.

Fourth Embodiment

FIG. 20 is a flowchart of the code division multiplexing method based onthe orthogonal codes according to the present embodiment.

The orthogonal codes based code division multiplexing method accordingto the present embodiment performs the code division multiplexing of thedemodulation reference signals in multiple layers of a resource block byusing an orthogonal matrix. As shown in FIG. 20, at step S2010, theorder of chips in a part of rows of a first orthogonal matrix is changedto obtain a second orthogonal matrix with the changed order of chips. Atstep S2020, the chips in the respective rows of the second orthogonalmatrix are multiplied by the demodulation reference signals in thecorresponding layers of the resource block in the time direction, so asto obtain code division multiplexing signals.

According to the present embodiment, the step S2010 may be implementedby the processing unit 1002 as shown in FIG. 10, and the step S2020 maybe implemented by the multiplexing unit 1006.

The orthogonal codes based code division multiplexing method accordingto the present embodiment may also include a step of changing the orderof chips by cyclically shifting the chips in a part of rows of the firstorthogonal matrix in the positive or reverse direction of the time axis,or by multiplying a part of rows of the first orthogonal matrix bynonzero numbers and cyclically shifting the chips in the respective rowsin the positive or reverse direction of the time axis, and multiplyingthe demodulation reference signals on the adjacent sub-carriers in therespective layers of the resource block by the chips in the first columnto the last column of the second orthogonal matrix alternately reversein the time direction.

For an orthogonal matrix of 4×4 orders and the four layers of a resourceblock, the orthogonal codes based code division multiplexing methodaccording to the present embodiment may also include a step of changingthe order of chips by cyclically shifting the chips in the last two rowsof the first orthogonal matrix by one column in the positive directionof the time, and multiplying the demodulation reference signals on thefirst sub-carrier in the first to the fourth layers of the resourceblock respectively by the chips in the first column to the fourth columnof the second orthogonal matrix in the positive direction of the time.

For the orthogonal matrix of 4×4 orders and the four layers of theresource block, the orthogonal codes based code division multiplexingmethod according to the present embodiment may also include a step ofchanging the order of chips by cyclically shifting the chips in the lasttwo rows of the first orthogonal matrix by one column in the positivedirection of the time, and multiplying the demodulation referencesignals on the second sub-carrier in the first to the fourth layers ofthe resource block respectively by the chips in the first column to thefourth column of the second orthogonal matrix in the reverse directionof the time.

For the orthogonal matrix of 4×4 orders and the four layers of theresource block, the orthogonal codes based code division multiplexingmethod according to the present embodiment may also include a step ofchanging the order of chips by cyclically shifting the chips in the lasttwo rows of the first orthogonal matrix by one column in the reversedirection of the time, and multiplying the demodulation referencesignals on the first sub-carrier in the first to the fourth layers ofthe resource block respectively by the chips in the first column to thefourth column of the second orthogonal matrix in the reverse directionof the time.

For the orthogonal matrix of 4×4 orders and the four layers of theresource block, the orthogonal codes based code division multiplexingmethod according to the present embodiment may also include a step ofchanging the order of chips by cyclically shifting the chips in the lasttwo rows of the first orthogonal matrix by one column in the reversedirection of the time, and multiplying the demodulation referencesignals on the second sub-carrier in the first to the fourth layers ofthe resource block respectively by the chips in the first column to thefourth column of the second orthogonal matrix in the positive directionof the time.

For the orthogonal matrix of 4×4 orders and the four layers of theresource block, the orthogonal codes based code division multiplexingmethod according to the present embodiment may also include followingsteps of: changing the order of chips by multiplying a part of rows ofthe first orthogonal matrix by nonzero numbers and cyclically shiftingthe chips in the respective rows by one column in the positive directionof the time, and multiplying the demodulation reference signals on thefirst sub-carrier in the first to the fourth layers of the resourceblock respectively by the chips in the first column to the fourth columnof the second orthogonal matrix in the positive direction of the time,and multiplying the demodulation reference signals on the secondsub-carrier in the first to the fourth layers of the resource blockrespectively by the chips in the first column to the fourth column ofthe second orthogonal matrix in the reverse direction of the time; andchanging the order of chips by multiplying a part of rows of the firstorthogonal matrix by nonzero numbers and cyclically shifting the chipsin the respective rows by one column in the reverse direction of thetime, and multiplying the demodulation reference signals on the thirdsub-carrier in the first to the fourth layers of the resource blockrespectively by the chips in the first column to the fourth column ofthe second orthogonal matrix in the positive direction of the time, andmultiplying the demodulation reference signals on the fourth sub-carrierin the first to the fourth layers of the resource block respectively bythe chips in the first column to the fourth column of the secondorthogonal matrix in the reverse direction of the time.

For the orthogonal matrix of 4×4 orders and the fifth to the eighthlayers of the eight layers of the resource block, the orthogonal codesbased code division multiplexing method according to the presentembodiment may also include a step of performing the same processingmanner for the demodulation reference signals in the fifth to the eighthof the resource block as the demodulation reference signals in the firstto the fourth layers of the resource block.

For the orthogonal matrix of 4×4 orders and the fifth to the eighthlayers of the eight layers of the resource block, the orthogonal codesbased code division multiplexing method according to the presentembodiment may also include a step of changing the order of chips bycyclically shifting the chips in the last two rows of the firstorthogonal matrix by one column in the reverse direction of the time,and multiplying the demodulation reference signals on the firstsub-carrier in the fifth to the eighth layers of the resource blockrespectively by the chips in the first column to the fourth column ofthe second orthogonal matrix in the positive direction of the time.

For the orthogonal matrix of 4×4 orders and the fifth to the eighthlayers of the eight layers of the resource block, the orthogonal codesbased code division multiplexing method according to the presentembodiment may also include a step of changing the order of chips bycyclically shifting the chips in the last two rows of the firstorthogonal matrix by one column in the reverse direction of the time,and multiplying the demodulation reference signals on the secondsub-carrier in the fifth to the eighth layers of the resource blockrespectively by the chips in the first column to the fourth column ofthe second orthogonal matrix in the reverse direction of the time.

For the orthogonal matrix of 4×4 orders and the fifth to the eighthlayers of the eight layers of the resource block, the orthogonal codesbased code division multiplexing method according to the presentembodiment may also include a step of changing the order of chips bycyclically shifting the chips in the last two rows of the firstorthogonal matrix by one column in the positive direction of the time,and multiplying the demodulation reference signals on the firstsub-carrier in the fifth to the eighth layers of the resource blockrespectively by the chips in the first column to the fourth column ofthe second orthogonal matrix in the reverse direction of the time.

For the orthogonal matrix of 4×4 orders and the fifth to the eighthlayers of the eight layers of the resource block, the orthogonal codesbased code division multiplexing method according to the presentembodiment may also include a step of changing the order of chips bycyclically shifting the chips in the last two rows of the firstorthogonal matrix by one column in the positive direction of the time,and multiplying the demodulation reference signals on the secondsub-carrier in the fifth to the eighth layers of the resource blockrespectively by the chips in the first column to the fourth column ofthe second orthogonal matrix in the positive direction of the time.

The order of executing respective steps of the above method does notlimit the scope of the present disclosure, and the above respectivesteps can be executed in parallel or in a different order.

The above respective steps may be implemented respectively orcollectively by the processing unit 1002 and the multiplexing unit 1006of the code division multiplexing device 1000.

According to the implementation of the present embodiment, a problem ofthe jitter on the time domain of the transmission power of a basestation can be effectively eliminated; meanwhile, the mapping methodpossesses the dual-orthogonality on the time domain and the frequencydomain, and the forward compatibility of 3GPP LTE-Advanced Release-9standard can be kept, and especially the usage efficiency of the poweramplifier at the base station side is improved.

Fifth Embodiment

FIG. 21 is a flowchart showing a de-multiplexing method according to thepresent embodiment.

The de-multiplexing method according to the present embodimentde-multiplexes the code division multiplexing signals in the multiplelayers of resource block by using an orthogonal matrix. As shown in FIG.21, in the step S2110, the code division multiplexing signals in themultiple layers of the resource blocks are received. In the step S2120,the chips in respective rows of the orthogonal matrix are multipliedcorrespondingly by the code division multiplexing signals in thecorresponding layers of the resource block in the time direction toobtain the demodulation reference signals. In the method according tothe present disclosure, the orthogonal matrix is obtained by changingthe order of chips in particular rows of another orthogonal matrix.

In the de-multiplexing method according to the present disclosure, forthe orthogonal matrix, the order of chips is changed by cyclicallyshifting the chips in a part of rows of another orthogonal matrix in thepositive or reverse direction of the time or by multiplying a part ofrows of another orthogonal matrix by nonzero numbers and cyclicallyshifting the chips in the respective rows in the positive or reversedirection of the time, and the de-multiplexing method further includes:multiplying the code division multiplexing signals on the adjacentsub-carriers in the respective layers of the resource block by the chipsin the first column to the last column of the orthogonal matrixalternately reverse in the time direction.

The above step S2110 may be implemented by the receiving unit 1906 ofthe de-multiplexing device 1900, and the step S2120 may be implementedby the de-multiplexing unit 1902.

The order of executing respective steps of the above method does notlimit the scope of the present disclosure, and the above respectivesteps can be executed in parallel or in a different order.

According to the implementation of the present embodiment, a problem ofthe jitter on the time domain of the transmission power of a basestation can be effectively eliminated; meanwhile, the mapping methodpossesses the dual-orthogonality on the time domain and the frequencydomain, and the forward compatibility of 3GPP LTE-Advanced Release-9standard can be kept, and especially the usage efficiency of the poweramplifier at the base station side is improved.

Sixth Embodiment

The orthogonal matrices in the foregoing embodiments all take Walshmatrices as examples; however, in fact, the methods according to thepresent disclosure are applicable to general orthogonal matrices. Inthis embodiment, an example of other type of an orthogonal matrix isgiven, and a corresponding mapping scheme for the orthogonal codes isconstructed by using the same method as the first embodiment.

FIG. 22 shows an example of a four-dimensional discrete Fouriertransform matrix.

In FIG. 22, an orthogonal matrix A2 is obtained through the samepermuting as FIG. 13. Of course, the orthogonal matrix A2 may also beobtained by the same method as that shown in FIG. 12. Firstly, the chipsin one row (for example, the chips in the second row [1, −1, 1, −1]) ofthe orthogonal matrix A (the first orthogonal matrix) are multiplied by(−1) to obtain the matrix A1 which is an orthogonal matrix. The columnsof the orthogonal matrix A1 are cyclically shifted by one bit to theleft (in the reverse direction of the time axis), and the matrix A2 isobtained. Then, on the basis of the A2, the method of the firstembodiment is repeated, and an orthogonal code mapping scheme on thecomplex domain can be obtained.

FIG. 23 shows a diagram of an orthogonal code mapping scheme on thecomplex domain obtained by repeating the method of the first embodimenton the basis of the orthogonal matrix A2 obtained in FIG. 22.

Here, the first resource block RB1 is taken as an example. The methodmay be that the demodulation reference signals in the first to thefourth layers of the resource block on the first sub-carrier F1 arerespectively multiplied by the first to the fourth columns of chips ofthe orthogonal matrix A2 in the positive direction of the time axis (thedirection of T1→T2→T3→T4).

Specifically, for the first sub-carrier F1, the demodulation referencesignals in the first layer of the resource block are respectivelymultiplied by the first to the fourth columns of chips [1, 1, 1, 1] inthe first row of the orthogonal matrix A2 in the positive direction ofthe time axis, the demodulation reference signals in the second layer ofthe resource block are respectively multiplied by the first to thefourth columns of chips [1, −1, 1, −1] in the second row of theorthogonal matrix A2 in the positive direction of the time axis, thedemodulation reference signals in the third layer of the resource blockare respectively multiplied by the first to the fourth columns of chips[j, −1, −j, 1] in the third row of the orthogonal matrix A2 in thepositive direction of the time axis, and the demodulation referencesignals in the fourth layer of the resource block are respectivelymultiplied by the first to the fourth columns of chips [−j, −1, j, 1] inthe fourth row of the orthogonal matrix A2 in the positive direction ofthe time axis.

The method may also be that the demodulation reference signals in thefirst to the fourth layers of the resource block on the secondsub-carrier F2 are respectively multiplied by the first to the fourthcolumns of chips of the orthogonal matrix A2 in the reverse direction ofthe time axis (the direction of T4→T3→T2→T1).

Specifically, for the second sub-carrier F2, the demodulation referencesignals in the first layer of the resource block are respectivelymultiplied by the first to the fourth columns of chips [1, 1, 1, 1] inthe first row of the orthogonal matrix A2 in the reverse direction ofthe time axis, the demodulation reference signals in the second layer ofthe resource block are respectively multiplied by the first to thefourth columns of chips [1, −1, 1, −1] in the second row of theorthogonal matrix A2 in the reverse direction of the time axis, thedemodulation reference signals in the third layer of the resource blockare respectively multiplied by the first to the fourth columns of chips[j, −1, −j, 1] in the third row of the orthogonal matrix A2 in thereverse direction of the time axis, and the demodulation referencesignals in the fourth layer of the resource block are respectivelymultiplied by the first to the fourth columns of chips [−j, −1, j, 1] inthe fourth row of the orthogonal matrix A2 in the reverse direction ofthe time axis. Here, the multiplication of the demodulation referencesignals in respective layers on the second sub-carrier respectively bythe first to the fourth columns of chips of the orthogonal matrix A2 inthe reverse direction of the time axis is equivalent to themultiplication of the demodulation reference signals in respectivelayers on the second sub-carrier respectively by the first to the fourthcolumns of chips of an orthogonal matrix A2′ in the positive directionof the time axis. The orthogonal matrix A2′ equals to an orthogonalmatrix obtained by arranging the first to the fourth columns of chips ofthe orthogonal matrix A2 reversely.

For the demodulation reference signals in the first to the fourth layersof the resource block on the third sub-carrier F3, the same operationsas those of the demodulation reference signals in the first to thefourth layers of the resource block on the first sub-carrier F1 arerepeated.

In addition, the chips in one row (for example, the chips in the secondrow [1, −1, 1, −1]) of the orthogonal matrix A (the first orthogonalmatrix) are multiplied by (−1) to obtain the matrix A1, and the columnsof the orthogonal matrix A1 are cyclically shifted by one bit to theright (in the positive direction of the time axis) to obtain anothermatrix A3

$\begin{bmatrix}1 & 1 & 1 & 1 \\1 & {- 1} & 1 & {- 1} \\{- j} & 1 & j & {- 1} \\j & 1 & {- j} & {- 1}\end{bmatrix}\quad$(the second orthogonal matrix). Then, on the basis of the A3, the methodof the first embodiment is repeated, and an orthogonal code mappingscheme on the complex domain can be obtained.

Here, the second resource block RB2 is taken as an example. The methodmay be that the demodulation reference signals in the first to thefourth layers of the resource block on the first sub-carrier F1 arerespectively multiplied by the first to the fourth columns of chips ofthe orthogonal matrix A3 in the reverse direction of the time axis (thedirection of T4→T3→T2→T1).

Specifically, for the first sub-carrier F1, the demodulation referencesignals in the first layer of the resource block are respectivelymultiplied by the first to the fourth columns of chips [1, 1, 1, 1] inthe first row of the orthogonal matrix A3 in the reverse direction ofthe time axis, the demodulation reference signals in the second layer ofthe resource block are respectively multiplied by the first to thefourth columns of chips [1, −1, 1, −1] in the second row of theorthogonal matrix A3 in the reverse direction of the time axis, thedemodulation reference signals in the third layer of the resource blockare respectively multiplied by the first to the fourth columns of chips[−j, 1, j, −1] in the third row of the orthogonal matrix A3 in thereverse direction of the time axis, and the demodulation referencesignals in the fourth layer of the resource block are respectivelymultiplied by the first to the fourth columns of chips [j, 1, −j, −1] inthe fourth row of the orthogonal matrix A3 in the reverse direction ofthe time axis. Here, the multiplication of the demodulation referencesignals in respective layers on the first sub-carrier respectively bythe first to the fourth columns of chips of the orthogonal matrix A3 inthe reverse direction of the time axis is equivalent to themultiplication of the demodulation reference signals in respectivelayers on the first sub-carrier respectively by the first to the fourthcolumns of chips of an orthogonal matrix A3′ in the positive directionof the time axis. The orthogonal matrix A3′ equals to an orthogonalmatrix obtained by arranging the first to the fourth columns of chips ofthe orthogonal matrix A3 reversely.

The method may also be that the demodulation reference signals in thefirst to the fourth layers of the resource block on the secondsub-carrier F2 are respectively multiplied by the first to the fourthcolumns of chips of the orthogonal matrix A3 in the positive directionof the time axis (the direction of T1→T2→T3→T4).

Specifically, for the second sub-carrier F2, the demodulation referencesignals in the first layer of the resource block are respectivelymultiplied by the first to the fourth columns of chips [1, 1, 1, 1] inthe first row of the orthogonal matrix A3 in the positive direction ofthe time axis, the demodulation reference signals in the second layer ofthe resource block are respectively multiplied by the first to thefourth columns of chips [1, −1, 1, −1] in the second row of theorthogonal matrix A3 in the positive direction of the time axis, thedemodulation reference signals in the third layer of the resource blockare respectively multiplied by the first to the fourth columns of chips[−j, 1, j, −1] in the third row of the orthogonal matrix A3 in thepositive direction of the time axis, and the demodulation referencesignals in the fourth layer of the resource block are respectivelymultiplied by the first to the fourth columns of chips [j, 1, −j, −1] inthe fourth row of the orthogonal matrix A3 in the positive direction ofthe time axis.

For the demodulation reference signals in the first to the fourth layersof the resource block on the third sub-carrier F3, the same operationsas those of the demodulation reference signals in the first to thefourth layers of the resource block on the first sub-carrier F1 arerepeated.

According to the implementation of the present embodiment, a problem ofthe jitter on the time domain of the transmission power of a basestation can be effectively eliminated; meanwhile, the mapping methodpossesses the dual-orthogonality on the time domain and the frequencydomain, and the forward compatibility of 3GPP LTE-Advanced Release-9standard can be kept, and especially the usage efficiency of the poweramplifier at the base station side is improved.

Seventh Embodiment

FIG. 24 shows a diagram according to the seventh embodiment of thepresent disclosure.

The seventh embodiment is one embodiment which is completely equivalentto the first embodiment. As shown in FIG. 24, another embodimentcompletely symmetrical with the first embodiment is obtained byadjusting the locations of respective matrices in FIG. 15, for example,replacing the matrices corresponding to the first sub-carrier F1 and thethird sub-carrier F3 of the first resource block RB1 by the matrixcorresponding to the second sub-carrier F2 of the second resource blockRB2, replacing the matrix corresponding to the second sub-carrier F2 ofthe first resource block RB1 by the matrix corresponding to the firstsub-carrier F1 of the second resource block RB2, meanwhile replacing thematrices corresponding to the first sub-carrier F1 and the thirdsub-carrier F3 of the second resource block RB2 by the matrixcorresponding to the second sub-carrier F2 of the first resource blockRB1, and replacing the matrix corresponding to the second sub-carrier F2of the second resource block RB2 by the matrix corresponding to thefirst sub-carrier F1 of the first resource block RB1. For thedemodulation reference signals in the first to the fourth layers of theresource block on the respective sub-carriers, the same operations asthose of the first embodiment are repeated, so the same effect as thefirst embodiment may be obtained. Specific details are no more describedherein.

Eighth Embodiment

The respective embodiments as described above are all designed withrespect to normal sub-frame structures in a LTE-A system. In the LTE-Asystem, there is a kind of special sub-frame structure, that is, thesub-frames with extended cyclic prefixes.

FIG. 25 is a diagram showing a sub-frame with an extended cyclic prefix.

The main difference between the sub-frame shown in FIG. 25 and thesub-frame structure shown in FIG. 3 is in that a resource block RB hasonly 12 OFDM symbols in the sub-frame with the extended cyclic prefix,while a resource block RB contains 14 OFDM symbols in the sub-framestructure shown in FIG. 3. The possible positions of the demodulationreference signals (DMRSs) in the sub-frame with the extended cyclicprefix are given in FIG. 25. Different from FIG. 8, one OFDM symbolcontains 4 DMRSs in FIG. 25, while one OFDM symbol contains only 3 DMRSsin FIG. 8.

The densities of the demodulation reference signals on the frequencydomain are different (changed from 3 to 4), which decides that themappings of the orthogonal codes multiplexing DMRSs are also different.In fact, by using the matrix C and the matrix E shown FIG. 12, theorthogonal code mapping scheme of the demodulation reference signals asshown in FIG. 25 may be obtained likewise.

FIG. 26 shows an orthogonal code mapping scheme of the demodulationreference signals as shown in FIG. 25.

As shown in FIG. 26, for the demodulation reference signals in the firstto the fourth layers of the resource block on the first sub-carrier F1,the chips in the last two rows of the orthogonal matrix A are cyclicallyshifted by one column in the positive direction of the time axis toobtain the orthogonal matrix C (as shown in FIG. 12), and thedemodulation reference signals in the first to the fourth layers of theresource block on the first sub-carrier F1 are respectively multipliedby the first column to the fourth column of chips of the orthogonalmatrix C in the positive direction of the time axis (the direction ofT1→T2→T3→T4).

Specifically, for the first sub-carrier F1, the demodulation referencesignals in the first layer of the resource block are respectivelymultiplied by the first to the fourth columns of chips [1, 1, 1, 1] inthe first row of the orthogonal matrix C in the positive direction ofthe time axis, the demodulation reference signals in the second layer ofthe resource block are respectively multiplied by the first to thefourth columns of chips [1, −1, 1, −1] in the second row of theorthogonal matrix C in the positive direction of the time axis, thedemodulation reference signals in the third layer of the resource blockare respectively multiplied by the first to the fourth columns of chips[−1, 1, 1, −1] in the third row of the orthogonal matrix C in thepositive direction of the time axis, and the demodulation referencesignals in the fourth layer of the resource block are respectivelymultiplied by the first to the fourth columns of chips [1, 1, −1, −1] inthe fourth row of the orthogonal matrix C in the positive direction ofthe time axis.

For the demodulation reference signals in the first to the fourth layersof the resource block on the second sub-carrier F2, the chips in thelast two rows of the orthogonal matrix A are cyclically shifted by onecolumn in the positive direction of the time axis to obtain theorthogonal matrix C (as shown in FIG. 12), and the demodulationreference signals in the first to the fourth layers of the resourceblock on the second sub-carrier F2 are respectively multiplied by thefirst column to the fourth column of chips of the orthogonal matrix C inthe reverse direction of the time axis (the direction of T4→T3→T2→T1).

Specifically, for the second sub-carrier F2, the demodulation referencesignals in the first layer of the resource block are respectivelymultiplied by the first to the fourth columns of chips [1, 1, 1, 1] inthe first row of the orthogonal matrix C in the reverse direction of thetime axis, the demodulation reference signals in the second layer of theresource block are respectively multiplied by the first to the fourthcolumns of chips [1, −1, 1, −1] in the second row of the orthogonalmatrix C in the reverse direction of the time axis, the demodulationreference signals in the third layer of the resource block arerespectively multiplied by the first to the fourth columns of chips [−1,1, 1, −1] in the third row of the orthogonal matrix C in the reversedirection of the time axis, and the demodulation reference signals inthe fourth layer of the resource block are respectively multiplied bythe first to the fourth columns of chips [1, 1, −1, −1] in the fourthrow of the orthogonal matrix C in the reverse direction of the timeaxis.

For the demodulation reference signals in the first to the fourth layersof the resource block of the third sub-carrier F3, the chips in the lasttwo rows of the orthogonal matrix A are cyclically shifted by one columnin the reverse direction of the time axis to obtain the orthogonalmatrix E (as shown in FIG. 12), and the demodulation reference signalsin the first to the fourth layers of the resource block on the thirdsub-carrier F3 are respectively multiplied by the first column to thefourth column of chips of the orthogonal matrix E in the positivedirection of the time axis (the direction of T1→T2→T3→T4).

Specifically, for the third sub-carrier F3, the demodulation referencesignals in the first layer of the resource block are respectivelymultiplied by the first to the fourth columns of chips [1, 1, 1, 1] inthe first row of the orthogonal matrix E in the positive direction ofthe time axis, the demodulation reference signals in the second layer ofthe resource block are respectively multiplied by the first to thefourth columns of chips [1, −1, 1, −1] in the second row of theorthogonal matrix E in the positive direction of the time axis, thedemodulation reference signals in the third layer of the resource blockare respectively multiplied by the first to the fourth columns of chips[1, −1, −1, 1] in the third row of the orthogonal matrix E in thepositive direction of the time axis, and the demodulation referencesignals in the fourth layer of the resource block are respectivelymultiplied by the first to the fourth columns of chips [−1, −1, 1, 1] inthe fourth row of the orthogonal matrix E in the positive direction ofthe time axis.

For the demodulation reference signals in the first to the fourth layersof the resource block on the fourth sub-carrier F4, the chips in thelast two rows of the orthogonal matrix A are cyclically shifted by onecolumn in the reverse direction of the time axis to obtain theorthogonal matrix E (as shown in FIG. 12), and the demodulationreference signals in the first to the fourth layers of the resourceblock on the fourth sub-carrier F4 are respectively multiplied by thefirst column to the fourth column of chips of the orthogonal matrix E inthe reverse direction of the time axis (the direction of T4→T3→T2→T1).

Specifically, for the fourth sub-carrier F4, the demodulation referencesignals in the first layer of the resource block are respectivelymultiplied by the first to the fourth columns of chips [1, 1, 1, 1] inthe first row of the orthogonal matrix E in the reverse direction of thetime axis, the demodulation reference signals in the second layer of theresource block are respectively multiplied by the first to the fourthcolumns of chips [1, −1, 1, −1] in the second row of the orthogonalmatrix E in the reverse direction of the time axis, the demodulationreference signals in the third layer of the resource block arerespectively multiplied by the first to the fourth columns of chips [1,−1, −1, 1] in the third row of the orthogonal matrix E in the reversedirection of the time axis, and the demodulation reference signals inthe fourth layer of the resource block are respectively multiplied bythe first to the fourth columns of chips [−1, −1, 1, 1] in the fourthrow of the orthogonal matrix E in the reverse direction of the timeaxis.

In FIG. 26, the mapping scheme for the orthogonal codes is unnecessaryto span the adjacent resource blocks RB. It is very easy to verify thatthe energy on 4 OFDM symbols of T1˜T4 are equal when the power of DMRSon the sub-carriers F1˜F4 are superposed. Thus, the peak powers areaveraged well.

Only the design for the DMRS mapping of the first to the fourth layersis described in the present embodiment. The mapping scheme of DMRS inthe fifth to the eighth layers in the second embodiment is easilyapplied to a case of being with an extended cyclic prefix.

The above embodiments of the present disclosure are only exemplarydescription, and their specific structures and operations do not limitthe scope of the disclosure. Those skilled in the art can recombinedifferent parts and operations of the above respective embodiments toproduce new implementations which equally accord with the concept of thepresent disclosure.

The embodiments of the present disclosure may be implemented byhardware, or a combination of hardware and software and firmware, andthe way of implementation does not limit the scope of the presentdisclosure.

The connection relationships between the respective functional elements(units) in the embodiments of the disclosure do not limit the scope ofthe present disclosure, in which one or multiple functional element(s)or unit(s) may contain or be connected to any other functional elements.

Although several embodiments of the present disclosure has been shownand described in combination with attached drawings above, those skilledin the art should understand that variations and modifications whichstill fall into the scope of claims and their equivalents of the presentdisclosure can be made to these embodiments without departing from theprinciple and spirit of the disclosure.

The invention claimed is:
 1. A communication apparatus comprising:memory that stores a first orthogonal matrix and a second orthogonalmatrix, each of which is a matrix with N rows and N columns where N is anatural number equal to or larger than 2, the second orthogonal matrixgenerated by cyclically shifting chips of particular rows of the firstorthogonal matrix; multiplying circuitry coupled to the memory, whereinthe multiplying circuitry, in operation, multiplies demodulationreference signals for a first layer group with the first orthogonalmatrix to obtain first multiplying results, and multiplies demodulationreference signals for a second layer group with the second orthogonalmatrix to obtain second multiplying results; mapping circuitry coupledto the multiplying circuitry, wherein the mapping circuitry, inoperation, superposingly maps the first multiplying results in a sametime period of a first subcarrier group in a resource block, andsuperposingly maps the second multiplying results in a same time periodof a second subcarrier group which is different from the firstsubcarrier group in the resource block, each of the first layer groupand the second layer group comprising N layers; and a transmitter which,in operation, transmits the resource block on which the multiplieddemodulation reference signals for the first layer group and themultiplied demodulation reference signals for the second layer group aremapped, the mapped demodulation reference signals to be used by acommunication partner apparatus to demodulate data signals that aresuperposed in each layer of the first layer group and the second layergroup in the resource block.
 2. The communication apparatus according toclaim 1, wherein the N is four, and the particular rows are a third rowand a fourth row of the first orthogonal matrix.
 3. The communicationapparatus according to claim 1, wherein the mapping circuitry, inoperation, superposingly maps the first multiplying results in the firstsubcarrier group including a plurality of subcarriers that are locatedat separate positions from each other on a frequency axis; and themapping circuitry, in operation, superposingly maps the secondmultiplying results in the second subcarrier group including a pluralityof subcarriers that are located at separate positions from each other onthe frequency axis.
 4. The communication apparatus according to claim 1,wherein the first layer group comprises N layers from a first layer toan Nth layer, and the multiplying circuitry, in operation, multiplies anLth row of the first orthogonal matrix and a demodulation referencesignal for an Lth layer to obtain the first multiplying results, where Lis a natural number equal to or larger than 1 and equal to or smallerthan N; and the second layer group comprises N layers from an (N+1)thlayer to a (2N)th layer, and the multiplying circuitry, in operation,multiplies an Mth row of the second orthogonal matrix and a demodulationreference signal for an (N+M)th layer to obtain the second multiplyingresults, where M is a natural number equal to or larger than 1 and equalto or smaller than N.
 5. The communication apparatus according to claim1, wherein the multiplying circuitry, in operation, multiplies thedemodulation reference signals for the first layer group with the firstorthogonal matrix, using a multiplying direction for an odd numberedsubcarrier included in the first subcarrier group, which is oppositefrom a multiplying direction used for an even numbered subcarrierincluded in the first subcarrier group; the multiplying circuitry, inoperation, multiplies the demodulation reference signals for the secondlayer group with the second orthogonal matrix, using a multiplyingdirection for an odd numbered subcarrier included in the secondsubcarrier group, which is opposite from a multiplying direction usedfor an even numbered subcarrier included in the second subcarrier group;and the multiplying direction for the odd numbered subcarrier includedin the first subcarrier group is same as the multiplying direction forthe even numbered subcarrier included in the second subcarrier group. 6.A communication method comprising: storing a first orthogonal matrix anda second orthogonal matrix, each of which is a matrix with N rows and Ncolumns where N is a natural number equal to or larger than 2, thesecond orthogonal matrix generated by cyclically shifting chips ofparticular rows of the first orthogonal matrix; multiplying demodulationreference signals for a first layer group with the first orthogonalmatrix to obtain first multiplying results, and multiplying demodulationreference signals for a second layer group with the second orthogonalmatrix to obtain second multiplying results; superposingly mapping thefirst multiplying results in a same time period of a first subcarriergroup in a resource block, and superposingly mapping the secondmultiplying results in a same time period of a second subcarrier groupwhich is different from the first subcarrier group in the resourceblock, each of the first layer group and the second layer groupcomprising N layers; and transmitting the resource block on which themultiplied demodulation reference signals for the first layer group andthe multiplied demodulation reference signals for the second layer groupare mapped, the mapped demodulation reference signals to be used by acommunication partner apparatus to demodulate data signals that aresuperposed in each layer of the first layer group and the second layergroup in the resource block.
 7. The communication method according toclaim 6, wherein the N is four, and the particular rows are a third rowand a fourth row of the first orthogonal matrix.
 8. The communicationmethod according to claim 6, wherein the mapping includes superposinglymapping the first multiplying results in the first subcarrier groupincluding a plurality of subcarriers that are located at separatepositions from each other on a frequency axis; and the mapping furtherincludes superposingly mapping the second multiplying results in thesecond subcarrier group including a plurality of subcarriers that arelocated at separate positions from each other on the frequency axis. 9.The communication method according to claim 6, wherein the first layergroup comprises N layers from a first layer to an Nth layer, and themultiplying includes multiplying an Lth row of the first orthogonalmatrix and a demodulation reference signal for an Lth layer to obtainthe first multiplying results, where L is a natural number equal to orlarger than 1 and equal to or smaller than N; and the second layer groupcomprises N layers from an (N+1)th layer to a (2N)th layer, and themultiplying includes multiplying an Mth row of the second orthogonalmatrix and a demodulation reference signal for an (N+M)th layer toobtain the second multiplying results, where M is a natural number equalto or larger than 1 and equal to or smaller than N.
 10. Thecommunication method according to claim 6, wherein the multiplyingincludes multiplying the demodulation reference signals for the firstlayer group with the first orthogonal matrix, using a multiplyingdirection for an odd numbered subcarrier included in the firstsubcarrier group, which is opposite from a multiplying direction usedfor an even numbered subcarrier included in the first subcarrier group;the multiplying further includes multiplying the demodulation referencesignals for the second layer group with the second orthogonal matrix,using a multiplying direction for an odd numbered subcarrier included inthe second subcarrier group, which is opposite from a multiplyingdirection used for an even numbered subcarrier included in the secondsubcarrier group; and the multiplying direction for the odd numberedsubcarrier included in the first subcarrier group is same as themultiplying direction for the even numbered subcarrier included in thesecond subcarrier group.